R1#sh run | b key
key chain prob3
 key 1
  key-string bosco
!
!
interface Ethernet0/1
 ip address 17.57.100.1 255.255.255.0
 ip authentication mode eigrp 100 md5
 ip authentication key-chain eigrp 100 prob3
 half-duplex
!



S6#sh run | b key
key chain Prob3
 key 1
  key-string bosco
!
interface Vlan16
 ip address 17.57.100.2 255.255.255.0
 ip authentication mode eigrp 100 md5
 ip authentication key-chain eigrp 100 Prob3
!